OK. I found your other thread and know your budget and that you are from India.
Just to explain what I'm working from:
Your CPU is an older comparatively slow CPU. It has two real cores and two more virtual cores through Hyperthreading. You also have only 4Gb of RAM. All of these put together and your H61 LGA1155 motherboard limits the CPU power of your system.
In any system, in general, it is limited by either processing (CPU and memory) or display (the Video Card). ( A few other systems are limited by storage speed, but you are not doing that)
Your motherboard will handle anything we want to do and more besides, so that doesn't matter.
To keep things simple we'll look at only NVidia Graphics cards. Your CPU is capable of driving a GTX 750ti to it's fullest extent (The limiting factor is the VGA). Your CPU is unlikely to drive a GTX 960 to its fullest extent (1080p, 60Hz, Ultra settings)(The limiting factor is the CPU)
The solution that MasterDell provided in the locked thread is good. fits your budget, and will allow you to use your CPU to its fullest extent and, if in the future you were to upgrade your CPU and RAM, you would grow into the capabilities of your VGA.